Apparatus for the electrical igniting of liquid propellents

ABSTRACT

An apparatus for electrical ignition of a liquid propellant has an ignition space formed of at least two chambers into which a liquid propellant is fed, the propellent being ignited in a first of the chambers in which, due to a constriction towards the adjacent chamber, a gas bubble is confined until by extensive reaction, the thermal capacity of the gas bubble is so great that the decomposition of the propellent proceeds further automatically at the boundary layer between the liquid and gas bubble, whereupon the reaction of the propellent is promoted in the second chamber which contains a system of channels producing a damming effect as a result of a wall friction occurring in the system of channels, such that the propellent present in the adjoining charge space is dependably and uniformly ignited.

United States Patent Germershausen et al.

APPARATUS FOR THE ELECTRICAL IGNITING OF LIQUID PROPELLENTS Inventors: Raimund Germershausen, Kaarst;

Jochen Schmitt, Schiefbahn; Wolfram Witt, Dusseldorf, all of Germany Rheinmetall GmbH, Dusseldorf, Germany Filed: Dec. 20, 1973 Appl. No: 426,914

Assignee:

Foreign Application Priority Data Dec. 30, 1972 Germany 2264332 U.S. Cl. 431/263, 431/353 Int. Cl. F23g 3/00 Field of Search 431/158, 263, 6, 353;

References Cited UNITED STATES PATENTS 6/1958 Schweitzer et a1 431/353 3/1964 Lindgren 431/353 X 3,531,229 9/1970 Berglund 431/158 X Primary Examiner-Edward G. Favors Attorney, Agent, or Firm-Ernest G. Montague; Karl 1 E Ross; Herbert Dubno [57] ABSTRACT An apparatus for electrical ignition of a liquid propellant has an ignition space formed of at least two chambers into which a liquid propellant is fed, the propellent being ignited in a first of the chambers in which, due to a constriction towards the adjacent chamber, a gas bubble is confined until by extensive reaction, the thermal capacity of the gas bubble is so great that the decomposition of the propellent proceeds further au tomatically at the boundary layer between the liquid and gas bubble, whereupon the reaction of the pr0pellent is promoted in the second chamber which contains a system of channels producing a damming effect as a result of a wall friction occurring in the system of channels, such that the propellent present in the adjoining charge space is dependably and uniformly ignited.

5 Claims, 2 Drawing Figures APPARATUS FOR THE ELECTRICAL IGNITING OF LIQUID PROPELLENTS The present invention relates to the electric ignition of liquid propellents and, more particularly to apparatus for such ignition.

For the ignition of solid, liquid and gaseous propellents by means of an electric spark, the spark gap is provided in fixed position in an ignition cap or in a cartridge casing or else in an electric igniter. The ignition carriers are destroyed or made unusable upon firing, so that for each additional shot a new carrier with a discharge path formed therein must be prepared.

It is an object of the present invention, while avoiding the above-mentioned disadvantages and defects, to improve the electric ignition of liquid propellents in such a manner that the ignition or propellent carrier remains indestructible and furthermore a dependably complete ignition of liquid propellents is assured.

In accordance with the present invention, this is achieved in that the liquid propellent is fed to an ignition space formed of at least two chambers and is ignited in the first chamber which is constricted towards the adjacent chamber, so that the formation of a gas bubble is restricted to the first chamber until the thermal capacity of the gas bubble produced therein is so great that the decomposition of the propellent occurs at the boundary layer between the liquid and gas bubble, whereupon transformation of the propellent in the second chamber to gas is brought about. The second chamber contains a system of channels producing a damming effect as a result of the wall friction in the system of channels, so that the propellent present in the adjoining charge space is dependably and uniformly ignited.

The constriction in accordance with the present invention extends in funnel-shaped fashion from both chambers with an angle enclosing the funnel of about 90 up to the opening, the opening cross section of which corresponds approximately to half the diameter of the electrode chamber.

Furthermore, in accordance with the present invention, the electrode is provided with a mushroom-like head plate, aligned with the housing constriction and so associated with the funnel-shaped housing constriction that the head plate lies opposite adjacent the constriction in the housing.

Finally, according to the present invention, the system of channels is broken up by a pile of balls or a system of pipes arranged in an axial direction which, entirely or partially fill up the inside of the large chamber.

The rapid, dependably complete ignition of the liquid propellent in the ignition charge space is determined by the diameter of the electrode chamber, by the housing constriction to the adjacent chamber, by the geometrical shape of the electrode, and finally by the damming action of the system of channels.

These and other objects will become more readily apparent from the following detailed description, reference being made to the accompanying drawing in which:

FIG. I is a longitudinal cross-sectional view through anignition charge housing in accordance with the presentinvention for liquid propellents; and

FIG. 2 is a section through a modification thereof.

The ignition housing 1 of FIG. 1 is arranged like a cartridge chamber directly behind the charge space of a gun barrel. The rear end surface of the ignition charge housing facing the breech of the gun is provided witha plastic ring 2. From the end] surface of the ring 2, a narrow cylindrical cavity extends inwardly into the housing 1, which comprises an electrode chamber 3, and is traversed in alongitudinal direction by an electrode 4 extending therein. The electrode 4 is covered by a mushroom-like head plate 40. In front of the head plate 4a there is formed a funnel-like housing constriction 5, which extends into a narrow passage opening 6. From the passage opening 6, the inside of the ignition charge housing 1 widens out in funnel shape into a cylindrical chamber 7, connected with a bundle constituting a plurality of pipes, the chamber 7 extending up to the front end surface of the housing 1 and its diameter and volume being several times greater than that of the electrode chamber 3, respectively. The feeding of the liquid propellent is effected either through the charge space, (not shown) or else directly via the line 8 into the ignition charge space. Finally, the ignition'of the liquid propellent is effected electrically in the electrode chamber 3, in the manner that a ground contact 10 is applied to the ignition charge housing 1 provided as a counter electrode and an ignition contact 9 is applied to the electrode 4. The plastic ring 2 insulates the two electrodes 1 and 4 from each other.

The funnel-shaped housing constriction 5 defines, referred to the funnel shape, an angle of about while the passage opening from the electrode chamber 3 into the adjacent chamber 7'has a free cross section which corresponds approximately to half the diameter of the electrode chamber.

The chamber 7 is traversed in a longitudinal direction by a system of channels 13 formed by the bundle of pipes extending parallel to each other or a pile of balls 23 between perforated plates 24 (FIG. 2).

The manner of action of the ignition device is as follows:

By applying an electric voltage to the electrode 4 by means of the ignition contact 9, an electric spark passes in the electrode chamber 3 and initiates the decomposi tion of the liquid propellent. The decisive factor for good and rapid ignition of the liquid in the electrode chamber is the geometrical shape and the central arrangement of the electrode in the electrode chamber 3. Due to the damming action of the housing constriction 5 towards the adjacent chamber, the conversion of the liquid propellent in gaseous phase is restricted to the electrode chamber 3, until substantially complete reaction has taken place here. As a result of this there is produced in the electrode chamber 3 a gas bubble whose heat capacitance and energy content are so great that the decomposition of the liquid propellent present in the other chamber can now also proceed automatically until complete reaction.

The reinforcing effect of the chamber 7 and of the bundles of pipes 13 contained therein is comparable to that of detonating charge in conventional propulsive charge primers, or else tothat of a priming charge in conventional propulsive charges. Only as a result of it, is the result achieved that the propellent is ignited reproducibly in the adjoining charge space, regardless of the geometry thereof and of the charge density selected. Another advantage of the chamber 7 is that the propellent is not ignited in point-form manner in the charge space, but rather uniformly over the entire cross section of the chamber 7.

ln contradistinction to the expense with the electrically ignited propellant charges previously used in which the main charge is ignited by a special ignition charge via an accessory charge, and therefore a total of three independent charges is required, the use of liquid and electrically ignited propellent in accordance with the present invention is extremely simple and economical, since there is required for this merely a single ignition charge space which can be constantly reused and which is provided with an electrode.

We claim: 1. A device for electrical ignition of liquid propellents comprising an ignition charge housing defining an ignition charge space having at least two chambers of different size arranged in said ignition charge housing, an electrode traversing centrally a smaller of said chambers constituting an electrode chamber and being connected with the adjacent of said chambers being of a larger volume and diameter, by means of an opening defining a housing constriction, and a system of channels extending in the larger of said chambers.

2. A device, as set forth in claim 1, wherein said housing constriction extends from both of said two chambers in funnel-like manner with an angle forming the funnels of about up to said openmg,

the cross section of said opening corresponds approximately to half the diameter of said electrode chamber.

3. A device, as set forth in claim 1, wherein said electrode has a mushroom-like head plate fitting said housing constriction and is disposed with respect to said housing constriction such that said head plate lies opposite and adjacent to said housing constriction.

4. A device, as set forth in claim 1, wherein said system of channels comprises a bundle of pipes arranged in an axial direction which at least partially or entirely fill up the inside of the larger of said chambers.

5. A device, as set forth in claim 1, wherein said system of channels comprises a pile of balls. 

1. A device for electrical ignition of liquid propellents comprising an ignition charge housing defining an ignition charge space having at least two chambers of different size arranged in said ignition charge housing, an electrode traversing centrally a smaller of said chambers constituting an electrode chamber and being connected with the adjacent of said chambers being of a larger volume and diameter, by means of an opening defining a housing constriction, and a system of channels extending in the larger of said chambers.
 2. A device, as set forth in claim 1, wherein said housing constriction extends from both of said two chambers in funnel-like manner with an angle forming the funnels of about 90* up to said opening, the cross section of said opening corresponds approximately to half the diameter of said electrode chamber.
 3. A device, as set forth in claim 1, wherein said electrode has a mushroom-like head plate fitting said housing constriction and is disposed with respect to said housing constriction such that said head plate lies opposite and adjacent to said housing constriction.
 4. A device, as set forth in claim 1, wherein said system of channels comprises a bundle of pipes arranged in an axial direction which at least partially or entirely fill up the inside of the larger of said chambers.
 5. A device, as set forth in claim 1, wherein said system of channels comprises a pile of balls. 